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Seasonal Weight Fluctuations And Their Influence On One’s State Of Health

About Obesity:

Obesity is a major health problem looming over the fitness of people throughout the globe. The figures suggest that the problems of obesity have bolstered up by around 50 percent in the past decade. Obesity can be a critical health condition that is arduous to recuperate if it sets in. Thus, it is always better to be precautious rather than seeking effective strategies to reduce obesity. In the advent of obesity becoming rampant in the population, it is important to understand the time throughout the life cycle when a person is more likely to gain weight. The pieces of evidence from several studies have suggested that factors like adolescence, pregnancy, etc. are some of the common periods when obesity sets in. Other reasons are attributed to environmental and behavioral changes like smoking, eating habits, etc.

What Is Seasonal Fluctuation In The Bodyweight?

Seasonal fluctuations in the bodyweight is a recent occurrence that has been observed generally in Western countries like the United States. But this variation in body weight due to seasonal changes is being noticed all over the world among the grown-ups belonging to 25 to 45 years of age. The shift in the season witnesses the change in the pattern of eating habits of an individual. It, in turn, affects the metabolic function of the body. When the metabolism is impaired, it eventually leads to weight gain or fluctuation in body weight. Many investigations were carried out to determine how the season affects the flux in body weight. The results indicated that the holidays and the winter seasons are particularly the time of the year when the weight surge in the adult population is maximum.[1]

How Seasonal Changes Affect The Metabolism Of The Body?

The oscillations in the climate are observed within the annual rotation of seasonal changes. With time, all animals, including humans, have evolved different mechanisms to withstand the harsh environmental changes. During the winter and season of fall, physical activities are significantly reduced as compared to the fitness activities in the summer season. The main reason that is traced back to the drop-down inactivity is attributed to the change in the metabolism of the body. The metabolic syndrome in people over 30 years of age is manifested in the form of weight gain. During the month of September and October, a large portion of the adult population is likely to or dispose of the overweight category if their metabolism is impaired.[2]

The human body faces the threat of seasonal changes by transforming the body into an insulin-resistant state. It helps the body to reduce the metabolism and acts as a fuel-efficient method during the change of seasons. It is a survival mechanism to regulate the effect of metabolism. When the body senses a shift in seasons, the brain signals the body to bolster insulin resistance. In turn, adipose tissues are stored in the form of fat in the body to be used during winter.[3,4]

A change in seasonal rhythm increases the calorie intake in humans. A test was carried out to study the effect of seasonal variation on the nutrient intake of humans. The 315 participants were instructed to maintain a week’s diary to note down everything they are, the time of their eating, and their state of hunger. After one week, when the results arrived, it was noticed that all the subjects showed an increase in the total intake of calories. During the fall season, the consumption of carbohydrates has significantly spiked up. The subjects reported that they experienced hunger pangs generally in the evening, even though they have had a large portion of the meal during the day. Although their stomach was packed with food, they still felt hungry. This was generally observed during the fall. Thus, the results suggested that modern heating solutions have no effect on the seasonal rhythmicity of food intake in humans. It can be a primary reason for obesity as it suppresses the mechanism to feel sated and compels you to eat more food.[5]

Causes Of Seasonal Weight Fluctuations

The weight fluctuations with the change in seasons are not only due to metabolic syndrome and heavy eating. But, there are various factors that play an active role in causing weight gain as the environment changes. The proportion of body fat relatively alters with the season. Especially the geographical locations like distance from the equator or other latitude lines also influence the variation in environmental conditions. But with scientific advances and technological modifications, human beings have reduced the effect of these fluctuations on their lives. The scientists have claimed that this misalignment of adaptation to seasonal changes has led to metabolic alterations as well as impaired thermoregulation that eventually promotes obesity.

Here are some common factors and how they affect the metabolism and body weight in humans.

  1. Intake of Food: The normal daily intake of food in a human comprises three or four basic meals depending on the adopted lifestyle and other social factors. The observation states that the morning breakfast is the most fulfilling and satiating meal of the day. Researchers have also recognized the fact that the amount of food eaten exhibits deviation with seasonal fluctuations, especially during autumn. The meal portion and calorie intake also showed good rise up during this season. The hypothalamus region of the human brain has hunger and satiety centers. The centers have receptors for chemical messengers or mediators that influence our feeding behavior. These mediators display a routine momentum with diet, body weight, and energy homeostasis. The mechanism of regulating seasonal food consumption and energy conservation differs from species to species as a strategy to combat climate change. The evidence of high consumption during autumn and winters has have been found in obese males as the concentration of leptin, cholesterol, and triglyceride was significantly higher in their bloodstream.
  2. Gut Function: The secretion of basal gastric acid, epithelial cell proliferation, and motility of the gastrointestinal part are synced in a particular rhythm. The rhythm is based on the time and portion of the meal ingested on a regular basis. Studies have shown that this synchronization is highly affected by the disturbance in the peripheral biological clock of the human body. The variation of season affects the biological clock of the body, which in turn regulates the expression of rhythmicity of the gastrointestinal tract. The upheaval in regulation puts our body at a higher risk of developing obesity. It is sometimes accompanied by altered craving food, constipation, diarrhea, and abdominal discomfort.
  3. Storage and Expenditure Of Energy: The food we eat is metabolism with the help of endocrine regulators. Hormones like glucagon, insulin, glucocorticoids, catecholamines, and thyroid hormones are correlated with the metabolic, digestive function of the body. The regulators that govern the secretion of digestive hormones in the body are in rhythm with the food intake. The adipose tissues present in the body are also influenced by the expression of biological clock genes in the body. It has been observed that with a change in season, the adipose tissues of the body grow in size. The fat cells are sensitive to exposure to cold and shorter daylight hours. Thus, during the winter and autumn season, a person is more susceptible to get obese or gain some extra weight.[6]
  4. Circadian Rhythm: Circadian clock is the seasonal rhythm of the hypothalamic pacemaker named the Suprachiasmatic nuclei. It is synchronized with solar time through retinal afferents and coordinates with the hormonal system of the body. The master clock controls phenomenons like processing of food, homeostasis, regulation of enzymes involved in glucose and cholesterol metabolism. It also influences food intake and dietary habits by sensing a change in the surrounding environment. Foods like excess glucose, caffeine, ethanol, thiamine, etc. are known to cause a shift in the circadian rhythm. When the disruption of circadian balance occurs, the metabolic changes lead to obesity or overweight as the craving for food increases.[7,8]

Seasonal Weight Fluctuations Due To Holiday And Winter Season

When obesity has emerged as one of the leading health problems across the globe, several studies were conducted to find out the reason behind the unexplained seasonal weight fluctuations. All results pointed out that the main culprit was the season of holidays. However, the holiday season is not a specific period of the year taken into consideration, but it generally starts from the end week of November and continues till the month of January. It is the time when individuals are more at risk of getting overweight and obese. The particular duration of the holiday is celebrated throughout the world. Festivals like Christmas, New year, and several social gatherings and parties are organized that are loaded with dense foods. The delicacies prepared during these festive occasions are high fat and high-calorie foods like pastries, cakes, candies, sugary and aerated drinks, chocolates, alcohol, etc.

A researcher named Yanovski published an article that focuses on the weight gain of people during the festive season prevailing between the months of November to January. He studied 195 individuals during the festive season and documented the fact that they all gained an average weight of 0.37kgs. He also stated that this additional weight is not easily lost within a year, and is around half of the weight a person yields throughout a single year.

Another similar study was carried out with a college population. The sample of students was examined throughout the period of Thanksgiving and New Year. The calorie intake during this period is quite noticeable as it is higher than in the spring season. College time is one of the critical points in the life of an individual when obesity is likely to knock your doors. It is due to the unhealthy lifestyle, lack of physical activity, and the festive season acts as an icing on the cake. In the cohort study done on college students, it was found that students between 18 to 29 years of age showed obesity. Winter is the particular season of the year when there is a drastic increase in calorie intake. Due to shorter day lengths, the physical activity also declines that eventually leads to gaining kilos. The studies revealed that some students gained remarkable weight during the winter season due to festive treats and lack of exercise. While some proportion of the students demonstrated no gain in body weight, but the percentage of body fat and fat mass was high in them.[9,10]

Seasonal Weight Fluctuation During Thanksgiving

In the United States, the fact is of great concern that every one out of five college student falls in the category of overweight or obese. The figures are increasing at an alarming rate, and the worst hit is the adult ones. The risk of obesity is also increasing their morbidity risk leading to early deaths by a heart attack, cardiac failure, etc. The season of Thanksgiving was the most crucial season for the younger population, as it contributed to enormous weight gain within a period of just 2 to 3 months every year. A survey on 94 college students during the winter break of Thanksgiving indicated that they gained a significant bodyweight of 0.5 kgs to 0.8kgs. The students who were already obese have gained more body weight as compared to the lean ones. It puts them to the risk of weight gain in the future along, with other disorders.[11]


Seasonal fluctuation in body weight is primarily seen during the season of fall and winter. While the main reason is the high-calorie intake during the festive meals of Thanksgiving and New Year, the metabolism of the body also plays a crucial role. Researchers have illustrated that the circadian rhythm or the biological clock of the body also contributes by regulating the feeling of appetite and satiety during seasonal changes.

Different studies were carried out on samples of subjects to study the effect of climatic change on body weight. All of them indicated that with a shift towards the colder season, the body weight as well as the fat deposit in the body increase leading to obesity.


  1. Yanovski, J. A., Yanovski, S. Z., Sovik, K. N., Nguyen, T. T., O’Neil, P. M., & Sebring, N. G. (2000). A prospective study of holiday weight gain. N Engl J Med, 342, 861-867
  2. Reilly, T., & Peiser, B. (2006). Seasonal variations in health-related human physical activity. Sports Medicine, 36(6), 473-485.
  3. Rintamäki, R., Grimaldi, S., Englund, A., Haukka, J., Partonen, T., Reunanen, A., … & Lönnqvist, J. (2008). Seasonal changes in mood and behavior are linked to metabolic syndrome. PLoS One, 3(1).
  4. https://www.hunimed.eu/news/seasons-can-affect-bodys-metabolism-watch-eat-stay-active-winter/
  5. de Castro, J. M. (1991). Seasonal rhythms of human nutrient intake and meal pattern. Physiology & behavior, 50(1), 243-248.
  6. Kanikowska, D., Sato, M., & Witowski, J. (2015). Contribution of daily and seasonal biorhythms to obesity in humans. International journal of biometeorology, 59(4), 377-384.
  7. Hastings, M., O’Neill, J. S., & Maywood, E. S. (2007). Circadian clocks: regulators of endocrine and metabolic rhythms. Journal of Endocrinology, 195(2), 187-198.
  8. Froy, O. (2010). Metabolism and circadian rhythms—implications for obesity. Endocrine reviews, 31(1), 1-24.
  9. Díaz-Zavala, R. G., Castro-Cantú, M. F., Valencia, M. E., Álvarez-Hernández, G., Haby, M. M., & Esparza-Romero, J. (2017). Effect of the holiday season on weight gain: a narrative review. Journal of obesity, 2017.
  10. Hull, H. R., Hester, C. N., & Fields, D. A. (2006). The effect of the holiday season on body weight and composition in college students. Nutrition & metabolism, 3(1), 44.
  11. Hull, H. R., Radley, D., Dinger, M. K., & Fields, D. A. (2006). The effect of the Thanksgiving holiday on weight gain. Nutrition journal, 5(1), 29.

Also Read:

Sheetal DeCaria, M.D.
Sheetal DeCaria, M.D.
Written, Edited or Reviewed By: Sheetal DeCaria, M.D. This article does not provide medical advice. See disclaimer
Last Modified On:September 11, 2020

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